Apparatus having first and second transceiver cells formed in a single integrated circuit

ABSTRACT

An apparatus having first and second transceiver cells formed in a single integrated circuit. In one example embodiment, an apparatus includes a first transceiver cell including a first set of components configured to enable communication on a first communication link in a network and a second transceiver cell formed underneath the first transceiver cell in a single integrated circuit (IC). The second transceiver cell is optically isolated from the first transceiver cell. The second transceiver cell includes a second set of components configured to enable communication on a second communication link in the network.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/146,674, filed Jan. 2, 2014, titled APPARATUS HAVING FIRST AND SECONDTRANSCEIVER CELLS FORMED IN A SINGLE INTEGRATED CIRCUIT, which is acontinuation of U.S. patent application Ser. No. 13/567,929, filed Aug.6, 2012, titled SEMICONDUCTOR-BASED OPTICAL TRANSCEIVER, which is acontinuation of U.S. patent application Ser. No. 11/368,930, filed Mar.6, 2006, titled SEMICONDUCTOR-BASED OPTICAL TRANSCEIVER, which claimsthe benefit of U.S. Provisional Application No. 60/658,558, filed Mar.4, 2005, titled SILICON ONLY (NO PC BOARD) OPTICAL TRANSCEIVER, all ofwhich applications are incorporated herein by reference in theirentireties.

BACKGROUND 1. The Field of the Invention

The embodiments disclosed herein relate generally to transceivers. Morespecifically, the embodiments disclosed herein relate to transceivercells that do not use a printed circuit board (PCB) for interconnectionsbetween the transceiver cells.

2. The Relevant Technology

Computing and networking technology have transformed our world. As theamount of information communicated over networks has increased, highspeed transmission has become ever more critical. Many high speed datatransmission networks rely on optical transceivers and similar devicesfor facilitating transmission and reception of digital data embodied inthe form of optical signals over optical fibers. Optical networks arethus found in a wide variety of high speed applications ranging from asmodest as a small Local Area Network (LAN) to as grandiose as thebackbone of the Internet.

Typically, data transmission in such networks is implemented by way ofan optical transmitter (also referred to as an electro-optictransducer), such as a laser or Light Emitting Diode (LED). Theelectro-optic transducer emits light when current is passed therethrough, the intensity of the emitted light being a function of thecurrent magnitude. Data reception is generally implemented by way of anoptical receiver (also referred to as an optoelectronic transducer), anexample of which is a photodiode. The optoelectronic transducer receiveslight and generates a current, the magnitude of the generated currentbeing a function of the intensity of the received light.

Various other components are also employed by the optical transceiver toaid in the control of the optical transmit and receive components, aswell as the processing of various data and other signals. For example,such optical transceivers typically include a driver (e.g., referred toas a “laser driver” when used to drive a laser signal) configured tocontrol the operation of the optical transmitter in response to variouscontrol inputs. The optical transceiver may also include a sensingphotodiode for monitoring the output of the optical transmitter.

The optical transceiver also generally includes an amplifier (e.g.,often referred to as a “post-amplifier”) configured to perform variousoperations with respect to certain parameters of a data signal receivedby the optical receiver. A TransImpedance Amplifier (TIA) may beimplemented to amplify signals received from the optical receiver. Acontroller circuit (hereinafter referred to as the “controller”)controls the operation of the laser driver and post amplifier.

The various components of the optical transceiver are often implementedas one or more integrated circuits or discrete components that areinterconnected using a PCB. The use of the PCB to interconnect thevarious ICs and discrete components, however, is often expensive andtime consuming during manufacture of the transceiver as each IC orcomponent must be individually mounted to the PCB.

In addition, individual optical transceivers are often enclosed in sometype of encasing or packaging for protection. The use of a PCB board tointerconnect the ICs and other components of the optical transceiver,however, often makes it so that the packaging or encasing of thetransceiver may potentially be larger, which may cause space problems ina host computing system coupled to the optical transceivers.

BRIEF SUMMARY

Embodiments disclosed herein relate to an apparatus having first andsecond transceiver cells formed in a single integrated circuit. In atleast some example embodiments, each transceiver cell may include a setof components integrated in a single integrated circuit that does notrequire a printed circuit board for interconnecting these components.

In one example embodiment, an apparatus includes a first transceivercell including a first set of components configured to enablecommunication on a first communication link in a network and a secondtransceiver cell formed underneath the first transceiver cell in asingle integrated circuit (IC). The second transceiver cell is opticallyisolated from the first transceiver cell. The second transceiver cellincludes a second set of components configured to enable communicationon a second communication link in the network.

In another example embodiment, an apparatus includes a first opticaltransceiver cell and a second optical transceiver cell. The firstoptical transceiver cell includes a first substrate on which thefollowing components are directly integrated: a first laser driver, afirst control module, a first post-amplifier, a first interconnectionbetween a transmitter and the first laser driver, a secondinterconnection between the first post-amplifier and a first receiver, athird interconnection between the first post-amplifier and the firstcontrol module, and a fourth interconnection between the first controlmodule and the first laser driver. The second optical transceiver cellincludes a second substrate on which the following components aredirectly integrated: a second laser driver, a second control module, asecond post-amplifier, a fifth interconnection between a second receiverand the second post-amplifier, a sixth interconnection between thesecond laser driver and a second transmitter, a seventh interconnectionbetween the second post-amplifier and the second control module, and aneighth interconnection between the second control module and the secondlaser. The second optical transceiver cell is optically isolated fromthe first optical transceiver cell and is formed on top of the firsttransceiver cell in a single integrated circuit (IC).

In yet another example embodiment, a method of multi-communicationtransceiver integrated circuit (IC) fabrication includes, in a singleIC, fabricating a first transceiver cell including a first substrate onwhich a first set of components is directly integrated, the firsttransceiver cell configured to communicate on a first communication linkat a first bitrate. The method also includes, in the single IC and ontop of the first transceiver cell, fabricating a second transceiver cellincluding a second substrate on which a second set of components isdirectly integrated. The second transceiver cell is configured tocommunicate on a second communication link at a second bitrate.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

Additional features and advantages will be set forth in the descriptionthat follows, and in part will be obvious from the description, or maybe learned by the practice of the embodiments disclosed herein. Thefeatures and advantages of the embodiments disclosed herein may berealized and obtained by means of the instruments and combinationsparticularly pointed out in the appended claims. These and otherfeatures of the embodiments disclosed herein will become more fullyapparent from the following description and appended claims, or may belearned by the practice of the embodiments disclosed herein as set forthhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the above and other advantages and features of thepresent invention, a more particular description of the invention willbe rendered by reference to specific embodiments thereof which areillustrated in the appended drawings. It is appreciated that thesedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting of its scope. The invention willbe described and explained with additional specificity and detailthrough the use of the accompanying drawings in which:

FIG. 1 illustrates an example optical transceiver IC in accordance withembodiments disclosed herein;

FIG. 2 illustrates another embodiment of the optical transceiver IC ofFIG. 1;

FIG. 3 illustrates an a further embodiment of the optical transceiver ICof FIG. 1;

FIG. 4 illustrates an additional embodiment of the optical transceiverIC of FIG. 1; and

FIG. 5 illustrates an embodiment of optical ports mounted on an opticaltransceiver IC.

DETAILED DESCRIPTION

Embodiments of the present invention extend to a semiconductor-basedoptical transceiver. The optical transceiver includes various componentsthat are integrated as a single integrated circuit (IC) without the useof a printed circuit board (PCB) for interconnecting the components. Insome embodiments, the optical transceiver includes a post-amplifier thatmay communicate with an optoelectronic transducer such as a photodiode,an electro-optic transducer driver that may communicate with anelectro-optic transducer such as a laser, and a control module thatcontrols the operation of the post-amplifier and electro-optictransducer driver, all integrated upon the same semiconductor die. Inother embodiments, the optical transceiver may further include aTransImpedance Amplifier (TIA), an optoelectronic transducer such as aphotodiode, a sense photodiode, and/or an electro-optic transducer allintegrated and/or mounted on the same semiconductor die.

Turning first to FIG. 1, an optical transceiver IC 100 is illustrated.Optical transceiver IC 100 may be configured to include severaldifferent components that are directly integrated or mounted onto asubstrate 110 of the optical transceiver IC 100. The components may beinterconnected using electrical interconnections that are also directlyintegrated onto the substrate 110. Accordingly, optical transceiver IC100 need not use a PCB for interconnections between the components thatare included on the single integrated circuit die. In some embodiments,optical transceiver IC 100 may be coupled to a host computing systemthat controls the operation of the optical transceiver. Opticaltransceiver IC 100 may be able to support 1G, 2G, 4G, 8G, 10G and higherbandwidth fiber optic links. Furthermore, optical transceiver IC 100 maybe able to support transmitter/receivers of any form factor such as XFP,SFP and SFF, without restriction.

As mentioned, optical transceiver IC 100 includes a substrate 110.Substrate 110 may be any reasonable substrate known in the art such assilicon or silicon germanium. In some embodiments, substrate 110 mayalso be gallium arsenide or indium phosphate. Note that the exactmaterial of substrate 100 will often be determined by the types ofcomponents that are integrated onto the substrate and the process usedto integrate the components. The embodiments disclosed hereincontemplate using different substrates as circumstances warrant.

As mentioned, various components, which will be described in more detailto follow, are integrated or mounted directly onto substrate 110. Thesecomponents may be integrated onto substrate 110 by any knownsemiconductor fabrication process. Examples of well-known semiconductorfabrication processes include photo lithography processes, etchingprocesses, and growth processes. In some embodiments, the components maybe fabricated using a complementary metal-oxide semiconductor process(CMOS) and/or a bipolar complementary metal-oxide semiconductor process(BiCMOS), both of which may be more cost effective than other processes,although that is not required. Advantageously, fabricating thecomponents of the optical transceiver IC 100 onto substrate 110 maycause lower power dissipation when the optical transceiver is operated.

Substrate 110 also includes electrical interconnections (describedbelow) between the various components that are also directly integratedonto the substrate. These electrical connections may be directlyintegrated onto substrate 110 by any semiconductor fabrication processknown in the art. Advantageously, directly integrating theinterconnections onto substrate 110 allows for interconnections withoutthe use of a PCB.

In addition, directly integrating the interconnections onto substrate110 may allow for increased performance. For example, because theinterconnections are necessarily close together, they are lesssusceptible to undesirable parasitic elements such as distributedcapacitance and inductance. In addition, the close proximity of theinterconnections helps to reduce cross-talk and Electro-MagneticInterference (EMI). The interconnections may also be fabricated usingless expensive processing as a result of their close proximity.

Although not illustrated in FIG. 1 (or in any of the subsequent figures)optical transceiver IC 100 will be enclosed in some type of packing whenimplemented. The packaging is used to protect the components andinterconnections integrated onto substrate 110. The packaging mayinclude various connections that are used to connect the components ofoptical transceiver IC 100 with components and systems external to theIC 100. These connections may be lead frames, pins, ball gird arrays, orany type of IC external connection known in the art.

Returning to FIG. 1, in one embodiment, optical transceiver IC 100includes a post-amplifier 130, an electro-optic transducer driver 140and a control module 150 that are directly integrated onto substrate110. Since lasers are in common usage, an electro-optic transducerdriver 140 may also be referred to as a “laser driver” to reflect thiscommon usage.

In operation, post-amplifier 130 is configured to communicate with anoptoelectronic transducer. Specifically, post-amplifier 130 receives anelectrical signal from an optoelectronic transducer such as a photodiodeusing interconnection 131. The post-amplifier 130 amplifies the signaland provides the amplified signal to the host computing system. Asmentioned above, interconnection 131 is directly integrated ontosubstrate 110. The optoelectronic transducer may be external to opticaltransceiver IC 100. In such cases, optical transceiver IC 100 may havean external interconnection (not illustrated) to facilitate connectionwith the optoelectronic transducer as mentioned previously.

Laser driver 140 is configured to communicate with an electro-optictransducer such as a laser or a Light Emitting Diode (LED).Specifically, laser driver 140 receives an electrical signal from a hostcomputing system and drives the electro-optical transducer usinginterconnection 141 with signals that cause the electro-opticaltransducer to emit optical signals representative of the information inthe electrical signal provided by the host. Interconnection 141 is alsodirectly integrated onto substrate 110. In embodiments where theelectro-optical transducer is external to optical transceiver IC 100, anexternal connection may be implemented as discussed previously.

In some embodiments, laser driver 140 is DC coupled to the electro-optictransducer. The laser driver may have a single ended output stage or adifferential output stage as circumstances warrant. DC coupling of thelaser driver to the electro-optic transducer helps to ensure that bothcomponents may be directly integrated onto substrate 110.

The behavior of post-amplifier 130 and the laser driver 140 may varydynamically due to a number of factors. For example, temperaturechanges, power fluctuations, and feedback conditions may each affect theperformance of these components. Accordingly, the optical transceiver IC100 may include a control module 120. Control module 120 is configuredto monitor the operation of the post-amplifier 130 and the laser driver140 using interconnections 121 and 122 respectively. In addition,control module 120 may provide control signals to and receive signalsfrom the post-amplifier 130 and the laser driver 140 also usinginterconnections 121 and 122. Control module 120 may include generalpurpose processing capabilities and therefore optical transceiver IC 100may be considered a computing device. As with the other interconnectionspreviously discussed, interconnections 121 and 122 are directlyintegrated onto substrate 110.

Turning now to FIG. 2, another embodiment of optical transceiver IC 100is depicted. The embodiment of FIG. 2 includes a Receive OpticalSubAssembly (ROSA) 125. ROSA 125 may include post-amplifier 130,TransImpedance Amplifier (TIA) 150 and an optoelectronic transducer 160or any combination of these three components as circumstances warrant.Note that hereinafter, an optoelectronic transducer will also bereferred to simply as a “receiver” 160 for simplicity. The embodiment ofFIG. 2 also includes the components previously described in relation toFIG. 1.

As illustrated, post-amplifier 130 is coupled to TIA 150 usinginterconnection 131. TIA 150 is configured to receive an electricalsignal from receiver 160 using interconnection 160 and to provideamplification and impendence matching of the signal prior to providingthe signal to the post-amplifier 130. In some embodiments, TIA 150 isdirectly integrated onto substrate 110 by any known semiconductorfabrication process in similar manner to the components discussed inrelation to FIG. 1. In such embodiments, interconnection 151, which isdirectly integrated onto substrate 110, would be coupled to an externalinterconnection if receiver 160 were implemented external to opticaltransceiver IC 100.

In other embodiments, however, TIA 150 may first be fabricated on aseparate substrate by any known fabrication process. TIA 150 may then bedirectly mounted onto substrate 110 by any mounting process known in theart in such a way that TIA 150 and post-amplifier 130 areinterconnected. In this way, TIA 150 is still integrated onto opticaltransceiver IC 100 without the need for a PCB to interconnect thecomponents.

In some embodiments, receiver 160 may be coupled to post-amplifier 130either indirectly through a TIA or directly. The receiver 160, which maybe a photodiode, acts as an optoelectronic transducer by transforming areceived optical signal into an electrical signal. Receiver 160 may bedirectly integrated onto substrate 110 by any known semiconductorfabrication process in similar manner to the components discussed inrelation to FIG. 1. Receiver 160 may be coupled to the post-amplifier130 by interconnections 131 and 151, which are also directly integratedonto substrate 110 as previously discussed.

As with TIA 150, receiver 160 may be first fabricated on a separatesubstrate by any known fabrication process. Receiver 160 may then bedirectly mounted onto substrate 110 by any mounting process known in theart in such a way that receiver 160 is interconnected with TIA 150and/or post-amplifier 130. Note that in this description and in theclaims, a component that is first fabricated on a separate substratethat is then subsequently mounted onto substrate 110 is considereddirectly integrated with the other components of substrate 110 into asingle integrated IC.

In further embodiments, both TIA 150 and receiver 160 may first befabricated onto a separate substrate by any process known in the art. Insuch a case, interconnection 151 would also be part of this substrate.The combination of the TIA 150 and receiver 160 could then be mounteddirectly onto substrate 110 by any mounting process known in the art.The mounted combination of the TIA 150 and receiver 160 would thenconnect with post-amplifier 130 using interconnection 131.

Turning now to FIG. 3, a further embodiment of optical transceiver IC100 is depicted. The embodiment of FIG. 3 includes a Transmit OpticalSubAssembly (TOSA) 145. TOSA 145 may include laser driver 140, sensephotodiode 170, and electro-optic transducer 180 or any combination ofthese three components as circumstances warrant. Note that hereinafter,an electro-optic transducer will also be referred to simply as a“transmitter” 180 for simplicity. The embodiment of FIG. 3 also includesthe components previously described in relation to FIG. 1.

As illustrated, sense photodiode 170 is connected to control module 120and laser driver 140 using interconnection 123 and interconnection 124respectively. As with the other interconnections, interconnections 123and 124 are directly integrated onto substrate 110. Sense photodiode 170is configured to monitor the performance of transmitter 180 usinginterconnection 171 and to provide this information to control module120 and/or laser driver 140. In some embodiments, sense photodiode isdirectly integrated onto substrate 110 by any known semiconductorfabrication process in similar manner to the components discussed inrelation to FIG. 1. In such embodiments, interconnection 171, which isdirectly integrated onto substrate 110, would be coupled to an externalinterconnection if transmitter 180 were implemented external to opticaltransceiver IC 100.

In other embodiments, sense photodiode 170 may be first fabricated on aseparate substrate by any known fabrication process. Sense photodiode170 may then be directly mounted onto substrate 110 by any process knownin the art. In this way, sense photodiode 170 is still integrated ontooptical transceiver IC 100 without the need for a PCB to interconnectwith other components.

Transmitter 180 may be coupled to laser driver 140. The transmitter 180,which may be a laser diode or LED, receives electrical drive signalsfrom laser driver 140 over interconnection 141 that cause transmitter180 to transmit optical signal representative of the information in theelectrical drive signals. Transmitter 180 may be directly integratedonto substrate 110 by any known semiconductor fabrication process insimilar manner to the components discussed in relation to FIG. 1.

Transmitter 180 may also be first fabricated on a separate substrate byany known fabrication process. Transmitter 180 may then be directlymounted onto substrate 110 by any process known in the art in such a waythat transmitter 180 is interconnected with laser driver 140 and sensephotodiode 170.

In further embodiments, both sense photodiode 170 and transmitter 180may first be fabricated onto a substrate by any process known in theart. In such a case, interconnection 171 would also be part of thissubstrate. The combination of the sense photodiode 170 and transmitter180 may then be directly mounted onto substrate 110 by any mountingprocess known in the art. The mounted combination of the sensephotodiode 170 and transmitter 180 would then connect with laser driver140 and control module 120 using interconnections 123, 124 and/or 141.

Turning now to FIG. 4, an additional embodiment of optical transceiverIC 100 is illustrated. The embodiment of FIG. 4 includes all of thecomponents previously discussed in relation to FIGS. 1-3, although therelative positions of some of the components on substrate 110 isillustrated differently. As previously discussed, the various componentsand interconnections of FIG. 4 may be directly integrated onto substrate110 by any semiconductor fabrication process known in the art such thata PCB board is not required for interconnecting the components. In someembodiments, TIA 150 and/or receiver 160 may be first fabricated onto aseparate substrate that is then directly mounted onto substrate 110 aspreviously described. In like manner, sense photodiode 170 and/ortransmitter 180 may also be first fabricated onto a separate substratethat is then directly mounted onto substrate 110 as previouslydescribed.

Note that FIG. 4 (and the proceeding figures) are drawn for ease ofillustration and are not necessarily drawn to actual scale orperspective. Accordingly, the embodiments where components such asreceiver 160 and transmitter 180 are first fabricated on a separatesubstrate and then directly mounted onto substrate 110 may not beexplicitly illustrated. A box is simply drawn to represent all thevarious embodiments of the various components. However, as has beenpreviously mentioned, the principles of the present inventioncontemplate both directly integrating components onto substrate 110 anddirectly mounting components previously fabricated on separate substrateonto substrate 110, both of which may be considered as integrated onto asingle IC without the use of a PCB for interconnections. In addition,the relative position of the various components in the figures is forease of illusion only. The principles of the present inventioncontemplate different locations for the various components on substrate110. Accordingly, the actual physical layout of the components onsubstrate 110 should not be used to limit the embodiments disclosedherein unless explicitly stated.

Although FIG. 4 illustrates all of the various components previouslydescribed, the embodiments disclosed herein also contemplate variousdifferent groupings of the components. For example, in one embodimentoptical transceiver IC 100 may include control module 120,post-amplifier 130, laser driver 140, TIA 150, receiver 160, andtransmitter 180. In this embodiment, the various components may befabricated as previously described. In addition, TIA 150 and/or receiver160 may be fabricated onto a separate substrate that is then directlymounted onto substrate 110 as previously described.

In another embodiment, optical transceiver IC 100 may include controlmodule 120, post-amplifier 130, laser driver 140, receiver 160, sensephoto diode 170 and transmitter 180. In this embodiment, the variouscomponents may be fabricated as previously described. In addition, sensephotodiode 170 and/or transmitter 180 may also be fabricated onto aseparate substrate that is then directly mounted onto substrate 110 aspreviously described. There may also be other groupings of components ascircumstances warrant.

Referring now to FIG. 5, an example embodiment of a receive optical port190A and a transmit optical port 190B are illustrated. Optical ports 190represent the physical interface between optical transceiver IC 100 andany optical fibers that are used to transmit optical signals fromoptical transceiver IC 100 and transmit optical signals to transceiver100. Optical ports 190 may be bonded to optical transceiver IC 100 inany way known in the art that will produce the required connection. Inthe illustrated embodiment, receiver 160 and transmitter 180 aredirectly mounted onto the top of substrate 110 as has been previouslydescribed. Receive optical port 190A, which is illustrated by a circlesurrounding receiver 160, is then mounted on top of receiver 160 by anyprocess known in the art. In like manner, transmit optical port 190B,which is illustrated by a circle surrounding transmitter 180, is mountedon top of transmitter 180. In some embodiments, both of the opticalports 190 may be aligned on the x-axis of IC 100 as this advantageouslyallows for ease of manufacture and connection to an optical fiber. Note,however, that other alignments are also contemplated by the embodimentsdisclosed herein.

Although not illustrated in FIGS. 1-4, optical transceiver IC 100 mayinclude other components such as capacitors as circumstance warrant. Forexample, in some embodiments AC capacitors in the range of 2000 pF maybe implemented to provide required capacitance in the transceiver. Theseparticular capacitors advantageously will fit in the limited space oftransceiver IC 100.

In some embodiments, optical transceiver IC 100 may be part of amultiple cell design. In such a design, one optical transceiver such asoptical transceiver IC 100 may be fabricated by any process known in theart on top of another optical transceiver, which in turn may haveanother optical transceiver fabricated on top of it, the resultingproduct being integrated into a single IC. Accordingly, any number ofoptical transceivers may be fabricated into a single IC as part of themultiple cell design. Advantageously, this design allows for parallelprocessing by using the different cells for different communicationlinks. For example, one cell may be configured to operate at 1 Gigabitper second (Gbps) while another cell was configured to operate at 2 Gbpsand so on.

Accordingly, the principles of the present invention relate to asemiconductor only optical transceiver. The components of the opticaltransceiver and corresponding interconnections are directly integratedonto a semiconductor substrate, thus forming an integrated IC.Advantageously this removes the need to implement a PCB forinterconnecting the components of the optical transceiver. As a result,manufacturing time and associated costs may be lowered as well knownsemiconductor fabrication processes may be implemented to fabricate theoptical transceiver ICs. In addition, the overall size of the opticaltransceiver may be lowered. Further, directly integrating the componentsand interconnects as an IC may cause lower power dissipation and lowerparasitic signal problems. Accordingly, the principles of the presentinvention are a significant advancement in the art of opticaltransceivers.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

What is claimed is:
 1. A transceiver comprising: a semiconductorsubstrate; a first optical transceiver cell including the followingcomponents integrated on the semiconductor substrate: a first laserdriver, a first post-amplifier, a first transmitter, a first receiver, afirst interconnection between the first transmitter and the first laserdriver, and a second interconnection between the first post-amplifierand the first receiver; and a second optical transceiver cell that isoptically isolated from the first optical transceiver cell, the secondoptical transceiver cell including the following components directlyintegrated on the semiconductor substrate: a second laser driver, asecond post-amplifier, a second receiver, a second transmitter, a thirdinterconnection between the second receiver and the secondpost-amplifier, and a fourth interconnection between the second laserdriver and the second transmitter; a first optical port that isconfigured for communication of optical signals to the first receiverfrom a first optical fiber; a second optical port that is configured forcommunication of optical signals from the first transmitter to a secondoptical fiber; a third optical port that is configured for communicationof optical signals to the second receiver from a third optical fiber;and a fourth optical port that is configured for communication ofoptical signals from the second transmitter to a fourth optical fiber,and wherein the first transmitter and the first receiver are configuredto communicate information on a first communication link and the secondtransmitter and the second receiver are configured to communicateinformation on a second communication link.
 2. The transceiver of claim1, wherein the first optical port, the second optical port, the thirdoptical port, and the fourth optical port are aligned along an axis. 3.The transceiver of claim 1, wherein: the first optical transceiver cellfurther includes a first sense photo diode that is integrated on thesemiconductor substrate; and the second optical transceiver cell furtherincludes a second sense photo diode that is integrated on thesemiconductor substrate.